Source of northern Iowa fish kill is a mystery for now

An unknown pollutant flowed from a stormwater sewer into a creek that runs through Hampton and killed a large number of fish last week, according to the Iowa Department of Natural Resources.

Some questions remain: The DNR has not been able to identify a source of the pollution, and the department is awaiting test results to identify the pollutant.

“We’re kind of at a loss,” said Jeremy Klatt, a DNR senior environmental specialist who investigated the situation.

He did not have an estimate of how many fish had been killed but said he saw “substantial” numbers of small fish and two northern pike: “I think it did kill everything.”

An angler reported the dead fish in Squaw Creek on the east side of Hampton on Thursday morning. Klatt tracked the fish kill about 1 1/2 miles upstream to a stormwater outfall on the west side of town.

Klatt noted Friday that fish were again swimming in the creek, which indicates a short-lived plume of contamination likely went into the creek and killed fish as it went downstream.

The stormwater sewer connects to several business sites in the area, but it also connects to farm field tiling outside the town, Klatt said. He saw no obvious contamination from any of the businesses.

“There could have been a spill or something out there in a field,” Klatt said.

The contaminated water had a reddish tint but had no distinctive odor. Tests of the water — including for potential herbicides — are expected to be complete in about two weeks.

The sewer’s purpose is to collect stormwater runoff. There was some rainfall near Hampton on Tuesday and Wednesday, but it totaled less than two-tenths of an inch, according to National Weather Service data.

Those who might know the source of the contamination can call the DNR’s Mason City field office at (641) 424-4073.

This article was originally published in Iowa Capital Dispatch.